Many different types of electrical and mechanical systems incorporate a sensing apparatus for detecting and measuring physical or chemical stimuli. Such sensing devices can be made to sense the presence and intensity of electrical or magnetic fields. Similarly, sensing apparatuses can be made to detect mechanical forces, measuring the temperature or flow of a liquid or gas, or register the acceleration of a solid body.
Over the years various types of sensing devices have been developed to accomplish these disparate tasks. The sensing apparatuses developed rely on a transducer or other sensing element having a specific preferred orientation in relation to the electrical or magnetic field or the a mechanical force to be sensed. Examples of electrical or magnetic field sensing elements are position and proximity sensors such as a Hall-effect cell, a magnetoresistor, a capacitive sensing element, and inductive sensing elements. An example of a mechanical force sensing element is a stress gauge that measures mechanical stress or weight of an object. Another example of a mechanical force sensing element is the accelerometer, which measures the acceleration of an object.
These sensing devices, then, typically have a preferred orientation for the sensing element relative to the electrical or magnetic field or to the physical force that is being sensed. The device thus must be oriented so that the sensing element has the preferred orientation if the sensor's sensitivity is to be optimized. There also may be extraneous electrical or magnetic fields or mechanical forces in the system with which the sensing device must accommodate, preferably by orienting the sensor relative to these extraneous fields or forces in a specific direction so as to reduce the sensor's sensitivity to the extraneous fields or forces. Such orientation can reduce sensing errors or noise caused by the movement of other objects or caused by the presence of other fields or forces within the vicinity of the sensing device.
Sensing apparatuses typically also rely on signal conditioning circuitry to amplify or otherwise condition the sensing signal that typically has too low a magnitude to overcome extraneous noise effects. The signal conditioning circuitry is also employed to condition a sensing signal that contains a large offset or other error signal that can overdrive sensitive monitoring equipment. Indeed, the signal conditioning circuitry can condition a sensing signal not otherwise conducive to transmission over an extended distance to a remotely located electrical device such a sensor monitoring circuit.
Thus, regardless of the specific nature of the stimulus to be sensed by a sensing apparatus, the device typically must include signal conditioning circuitry connected to a sensing element, which in turn, is positioned in a preferred orientation so as to maximize its sensing sensitivity.
Prior art sensing apparatuses typically are manufactured with the sensing element and the signal conditioning circuitry on a common-plane wafer, both which are interconnected via conductors (e.g., using metal or other conductive traces) formed on the same plane. These prior art devices typically are then installed in an electrical or a mechanical system with the sensing element oriented in a specific direction relative to the field being sensed. For a sensing apparatus having the sensing element and signal conditioner formed on a common-plane, then, the orientation also determines the orientation of the signal conditioner.
The amount of area occupied by the sensing element is ordinarily much smaller than the area required for the signal conditioning circuitry. Common-plane orientation of both the sensing element and the signal conditioning circuitry, therefore, generally produces a sensing apparatus having a larger cross section than could otherwise be achieved were the sensing element and the signal conditioner separately oriented in directions. This is an increasingly important consideration because sensing apparatuses are employed in electrical and mechanical systems that are increasingly smaller and thus require ever more compact sensing devices. In addition, the sensing apparatuses are increasingly tasked with ever more complicated functions, necessitating accordingly more complex circuitry. There is thus a need to reduce the size of sensing apparatuses by, for example, separately orienting the sensing element and the signal conditioning circuitry.
At the same time, though, the reduced size can not come at the expense of the structural integrity of the sensing apparatus because sensing devices typically are used in electrical and mechanical systems that are subject to harsh conditions such as extreme vibrations and accelerations, extreme temperature variations, exposure to harsh chemicals. Thus, while there is an ever greater need to reduce the overall size of the sensing apparatus, there is a corresponding need to maintain or enhance the structural integrity of the device.